Motor assembly and method of manufacturing the same

Abstract

A method of manufacturing a motor assembly comprising a motor and an impeller coupled to a rotation shaft of the motor, the method includes disposing a plurality of balls in a ring-shaped groove formed in a surface of the impeller; rotating the impeller at a speed greater than a resonant rotation speed to move the balls to a compensation position for compensating for an eccentricity in the motor assembly; and fixing the balls at the compensation position in the groove.

What is claimed is: 
     
       1. A method of manufacturing a motor assembly comprising a motor and an impeller coupled to a rotation shaft of the motor, the method comprising:
 disposing a plurality of balls in a ring-shaped groove formed in a surface of the impeller; 
 disposing a transparent cover to cover the groove and to allow identifying a position of the balls inside the groove; 
 rotating the impeller at a speed greater than a resonant rotation speed of the impeller to move the balls to a compensation position for compensating for an eccentricity in the motor assembly; 
 identifying the compensation position of the balls through the transparent cover by rotating the impeller at the speed greater than the resonant rotation speed, using at least one of a high-speed camera or a stroboscope; and 
 fixing the balls so that the balls are maintained at the compensation position in the groove, 
 wherein the fixing of the balls at the compensation position comprises:
 removing the transparent cover after stopping the impeller; 
 moving the balls to the compensation position in the groove; and 
 fixing the balls at the compensation position using a fixing member by covering the groove with a cover member in which the fixing member is formed, 
 
 wherein the fixing member comprises a pressing member that fixes the position of the balls by pressing the balls. 
 
     
     
       2. The method of  claim 1 , wherein fixing the balls at the compensation position comprises using an adhesive to fix the balls at the compensation position. 
     
     
       3. The method of  claim 2 , further comprising injecting the adhesive into the groove before the impeller is rotated, and
 wherein the fixing of the balls at the compensation position comprises maintaining a rotation speed of the impeller until the adhesive is hardened with the balls fixed in the compensation position. 
 
     
     
       4. The method of  claim 1 , wherein the fixing member is spaced apart at equal intervals in a circumferential direction of the groove. 
     
     
       5. The method of  claim 1 , wherein a thickness of the pressing member before pressing the balls is greater than a difference between a height from a bottom surface of the groove to an inner surface of the cover member and a diameter of the balls. 
     
     
       6. A method of manufacturing a motor assembly comprising a motor and an impeller coupled to a rotation shaft of the motor, the method comprising:
 disposing a plurality of balls in a ring-shaped groove formed in a surface of the impeller; 
 disposing a transparent cover to cover the groove and to allow identifying a position of the balls inside the groove; 
 rotating the impeller at a speed greater than a resonant rotation speed of the impeller to move the balls to a compensation position for compensating for an eccentricity in the motor assembly; 
 identifying the compensation position of the balls through the transparent cover by rotating the impeller at the speed greater than the resonant rotation speed, using at least one of a high-speed camera or a stroboscope; and 
 fixing the balls so that the balls are maintained at the compensation position in the groove, 
 wherein the fixing of the balls at the compensation position comprises:
 removing the transparent cover after stopping the impeller; 
 moving the balls to the compensation position in the groove; and 
 fixing the balls at the compensation position using a fixing member by covering the groove with a cover member in which the fixing member is formed, 
 
 wherein the fixing member comprises a plurality of protrusions that protrude from an inner surface of the cover member and are arranged at equal intervals in a circumferential direction, 
 wherein a pair of protrusions adjacent to each other among the plurality of protrusions are formed on both sides of the balls to limit positional movement of the balls, 
 wherein a gap between the pair of protrusions is greater than or equal to a radius of the balls and less than or equal to a diameter of the balls, and 
 wherein a height of a protrusion of the pair of protrusions from an inner surface of the cover member is greater by a length of 10% to 20% of the diameter of the balls than a difference between a height from a bottom surface of the groove to an inner surface of the cover member and the diameter of the balls. 
 
     
     
       7. A motor assembly comprising:
 a motor; and 
 an impeller coupled to a rotation shaft of the motor, 
 wherein the impeller comprises:
 a body comprising a blade, and a ring-shaped groove formed in a surface of the body; 
 a cover member configured to cover the groove; 
 a plurality of balls disposed inside the groove; and 
 a fixing member configured to fix the balls so that positions of the balls are maintained inside the groove, 
 
 wherein the fixing member comprises a plurality of protrusions that protrude from an inner surface of the cover member and are arranged at equal intervals in a circumferential direction, 
 wherein a pair of protrusions adjacent to each other among the plurality of protrusions are formed on both sides of the balls to limit positional movement of the balls, and 
 wherein a gap between the pair of protrusions is greater than or equal to a radius of the balls and less than or equal to a diameter of the balls. 
 
     
     
       8. The motor assembly of  claim 7 , wherein the fixing member comprises an adhesive configured to adhere the balls to an inside of the groove. 
     
     
       9. The motor assembly of  claim 8 , wherein the adhesive is disposed on an outer circumferential wall inside the groove. 
     
     
       10. The motor assembly of  claim 7 , wherein the fixing member is disposed on an inner surface of the cover member and is spaced apart at equal intervals in the circumferential direction of the groove. 
     
     
       11. The motor assembly of  claim 7 , wherein the fixing member comprises a pressing member configured to fix a position of the balls by pressing the balls. 
     
     
       12. The motor assembly of  claim 11 , wherein a thickness of the pressing member before pressing the balls is greater than a difference between a height from a bottom surface of the groove to an inner surface of the cover member and the diameter of the balls. 
     
     
       13. The motor assembly of  claim 7 , wherein a height for a protrusion of the pair of protrusions from an inner surface of the cover member is greater by a length in a range from 10% to 20% of the diameter of the balls than a difference between a height from a bottom surface of the groove to an inner surface of the cover member and the diameter of the balls. 
     
     
       14. A vacuum cleaner comprising a motor assembly, wherein:
 the motor assembly comprises a motor and an impeller coupled to a rotation shaft of the motor, and 
 the impeller comprises:
 a body including a ring-shaped groove formed in a surface of the body; 
 a cover member configured to cover the groove; 
 a plurality of balls disposed inside the groove; and 
 
 a fixing member configured to fix the balls inside the groove, 
 wherein the fixing member comprises a plurality of protrusions that protrude from an inner surface of the cover member and are arranged at equal intervals in a circumferential direction, 
 wherein a pair of protrusions adjacent to each other among the plurality of protrusions are formed on both sides of the balls to limit positional movement of the balls, and 
 wherein a gap between the pair of protrusions is greater than or equal to a radius of the balls and less than or equal to a diameter of the balls.